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4 Io Drawing.

Patented Feb. 28, I933 unrran STATES PATENT OFFICE.

mu 1%. KcKEE, or NEW YORK,

H. Y AND mm H. MORSE, OF NUTLEY, NEW

JERSEY, ASSIGR'ORS TO ALEXANDEB HERZ, OF NEW ROCHELLE, NEW YORK DEPILA'IOBY ANDHETHOD OI COMPOUNDTNG THE SAME This invention relates to a new and improved depilatory compound for removing hair from the human body and to the process of preparing the same.

The primary object tion is to rovide a depilatory compound which is e ective and rapid in its action, relatively stable over long periods, non-toxic and non-irritating when applied to the human skin, and particularly a apted for preparation as an attractive toilet article.

During recent ears, the recognition, particularly by mem ers of the feminine sex, of depilatory compounds as almost indispensable toilet preparations has become increasingly widespread. As a result of this increased use of depilatories, and especiall cause of the exacting requirements 0 the feminine sex with respect to toilet preparations, the standard of quality demanded of depilatory compounds has been raised to a materially higher level than has been attained by depilatory compounds heretofore available. I.

In order to satisfy present day requirements, a depilatory compound should have the following characteristics: It should be efiective and rapid in its action; it should be relatively stable on exposure to air; it should be non-toxic and substantially nonirritating when applied to the human skin; it should be light in color and preferablv pure white; and it should be odorless or at least susceptible to effective perfuming.

The depilatory compounds w ich heretofore have generally been employed for the purpose described fail by a considerable margin to meet the requirements outlined above. The most commonly used depilatories invariably employ a sulfur compound, such as an alkali sulfid, as the active depilating agent with 'the result that such depilatories have an exceedin ly disagreeable and nauit is impossible to overcome despite the many attempts. that have been made to mask it by the addition, of perfumes and deodorants. For this reason the sulfur-containing depilatories are hi hly objectionable as toilet preparations. oreover, they are otherwise objectionable, when of the present inven- Appl-lcatlon filed. January 4, 1932. Serial No. 584,758..

considered as articles for the toilet, on account of their color which generally ranges from a dull blue to a dark gra In addition, they are readily decompose and are renderedpartially or wholly ineffective by ex- Egsure to air and are therefore required to kept thoroughly sealed from the atmosphere to prevent deterioration. Finally,

' some of the sulfur-compounds employed are active poisons and cannot be used freely on the human skin, particularly about the lips, without producing ill or unpleasant effects.

We are aware that depilating agents which will not possess the diagreeable characteristics of the sulfur-containing agents when used in de ilatory compounds has been proposed,- and t at thallium salts have been used for this purpose. However, thallium salts are objectionable in that they are poisonous and also because the do not act primarily upon the hair but rat er upon the nerves or blood vessels surrounding the roots of the hair whereby after several applications the individual hairs become loosened from their follicles and may be pulled out. Consequenty, which enters the system and becomes effective only by operating as a drug upon the roots of the hair is not a depilatory in the sense in which the term is generally understood and in which we use it herein.

We have discovered that the above referred to objections and disadvantages which have heretofore attended depilatory compounds can successfully be overcome, and have produced a depilatory compound which possesses all of the characteristics of acompletely satisfactory depilatory as set forth above.

In its fundamental aspect, the theory of our invention is based on the disintegrating effect of divalent tin in alkaline solution on the keratin molecule of the hair, and more a thallium salt compound of this nature in a nt in our new re arationarelatively SOfilb e stannite, pre era ly an alkali stannite such as sodium stannite, and. combine it with other ingredients to render the reparation stable and impart to it a su stantlal rapidity of action upon the hair'without producing an irritating effect upon the surface of the skin.

The employment of a relatively soluble stannite as an active depilatin in advantages which are not 0 tamed by the use of other divalent tin compounds. For example, insoluble divalent tin compounds, such as some of the stannous salts, are not suitable since they cannot be brou ht into effective contact with the hair. oreover, stannous chloride, which is the most common divalent tin salt and is quite readil soluble in water, is not suitable foruse y itself since it does not attack the hair. vHowever,

when combined .with an alkali-forming metal hydroxid the stannite thus produced Wlll possess a disintegrating effect upon the hair, the

rate of the disintegration eing primarily dependent upon the degree of solubility of the particular stannite formed. For example, the nearly insoluble calcium stannite, Wlnch would be formed by combining stannous chloride with calcium hydroxid, will act upon the hair, but the action is much too slow to be of practical use as a depilating a ent of the type here referred to. The speed of destruction of the hair by a depilating agent of the character described depends upon the time required for such agent to penetrate the hair in substantial concentration. While the speed of action may be increased to some extent by increasing the alkalinity of the depilating mixture, the limits; to which such alkalinity may go without}; rendering the mixture too caustic and irritant to the human skin are low. I

In order to provide a depilating mixture which will be relati ely rapid in its action without being excesslvely alkaline, we employ as the active depilating agent a relatively soluble stannite, and preferably one that is considerably more soluble than calcium stannite. As stated above, our preference is for an alkali stannite and especially sodium stannite though otherstannites more soluble than calcium stannite, such as barium stannite, work well. In some cases a mixture, such as a mixture of barium stannite and a small amount of sodium stannite, is particularly effective as it is rapid in action but not irritating to the skin.

A buffer action to control the alkalinity may be obtained by the addition of any amphoteric metal in a form in which reaction will readily take place with excess caustic alkali and such will permit the addition of substantial proportions of strong alkali, if desired, without having free caustic alkali present in the mixture in sufficient amount agent results I to attack the skin surfaces during the time I erence is for tin. In the event that tin alone is employed as a buffer, it is preferably used in the form of stannous hydroxid.

In order to facilitate the penetration of the active depilating agent into the hair structure we prefer to include in the depilatory mixture a suitable wetting agent i. e. a surface tension reducing agent. various known wetting agents may be employed, as willbe apparent, but we prefer to use a pure soap, such as sodium oleate. Such material not only serves as an advantageous wetting agent and softener for the hair but it also has an emollient and soothing action on the skin and serves to prevent the other constituents present in the mixture from producing irritation.

In preparing our depilatory mixture in the form of an attractive toilet article we increase the consistency of the preparation by adding an inert filler in an amount suili In the preferred practice .of compounding our depilatory preparation, weform sodium stannite by reacting stabilized stannous hy-v droxid with sodium hydroxid. While sodium stannite obviously may be derived by mixing stannous ehlorid, which is the com-- mon source of stannous compounds, with caustic soda, this is disadvantageous in the practice of the present invention'since brown hydrated stannic oxid and gray metallic tin are ordinarily formed 'in addition to the normal sodium stannite, and both of the former will impart an undesirable dark color to the compound. Moreover, the normal sodiumstannite which is produced as a result of this reaction is relatively unstable. Consequently, we prefer to first prepare stannous hydroxid and then stabilize this compound with an alkali salt of a polybasic organic acid, such as the hydroxy acids, tartaric or citric acid. The resulting stabilized stannous hydroxid is then reacted with sodium hydroxid solution which is then mixed with the other ingredients as suggested above and in the manner hereinatfer described in detail. A

The following specific example of the preoleate converts the creamy liquid into a thin fol-red method of compounding our new depilatory compound as an attractive toilet article may be considered as illustrative of the invention:

Stannous hydroxid is prepared by dissolving 100 g. of tin salt (SnCl 2H O) in 4 00 cc. of water, and slowly adding this solution to a solution of 60 g. of commercial soda ash (dry sodium carbonate) in 1000 cc.'of

water. Just prior to the addition of the stannous chlorid solution' to the soda ash solution, the former is diluted with an additional 400 cc. of water. The stannous hydroxid separates as a white gelatinous precipitate which settles rapidly. This precipitate is washed by decantation five or six times and finally allowed to settle, after which the excess liquid is drawn off from above the preci iita'te. The foregoing reaction is preferab y conducted at about ordinary room temperature.

In order to stabilize the stannous hydroxid the precipitate formed as above is mixed with 46 g. of sodium potassium tartrate (Rochelle salts) dissolved in a small amount of water. The stabilizing action which results from this treatment is probably similar to that of Rochelle salts on cupric oxid in Fehlings 'solution, that is, it is apparently due to the formation of complex tartaric acid salts stable in solutions of modified alkalinity. The

volume of the precipitate formed as a result mixed together in order to produce the desired soluble sodium stannite. Only about half of the stannous hydroxid dissolves in this amount of alkali; the balance acting as a buffer to control the alkalinity. The soluble sodium stannite resulting from this reaction is not the normal unstable sodium stannite but is apparently a more stable form of stannite. It is completely stable, any tendency toward decomposition having been checked by the addition of the Rochelle salts to the compound, and its effective depilatory action will remain unimpaired in the compound for any length of time provided the compound is not given a long exposure to direct sunlight.

To the thus prepared product are added 10 g. of sodium oleate (powdered white soap) and thoroughly incorporated therewith by stirring. This addition of sodium The consistency of'the paste may also be Y modified by the addition of glyeerine or other emollients.

A depilatory thus prepared will be white, odorless, substantially non-irritating, nontoxic, stable except upon long exposure to sunlight,-and extremely rapid in its action upon the hair, destroying the structure of the hair rather than completely dissolving it but enabling the hair, a few minutes after application, to be completely removed by a slight rubbing action on the skin. Having the above characteristics, the improved compound may be dispensed as an attractive toilet cream.

In using the term odorless in the appended claims, we refer to a compound embodying the invention described above and therefore intend to include all such compounds whether with or without an added perfuming agent.

.By the expression for use in removing hair the skin, for to be practicable for such a purpose as is referred to, a compound must act mildly on the skin and yet eflectively upon the hair in a very few minutes. However, we do not wish it to be understood that the .appended claims are thereby limited to compounds whose action is more rapid than the use specified reasonably requires.

We claim:

1. A depilatory compound for use in rapidly removing hair from the human body and containing as an active depilating agent a relatively concentrated alkaline solution of a stannite more soluble than calcium-stannite, and a stabilizing agent for said stannite.

2. A depilatory compound for use in rapidly removing hair from the human body and containing as an active depilating agent a relatively concentrated alkaline solution of a stannite more soluble than calcium stannite, and a stabilizing agentfor said stannite comprising an alkali salt of a polybasic hydroxy organic acid.

3. A de-pilatory compound for use in rapidly removing hair from the human body and containing as an active depilating agent a relatively concentrated alkaline solution of a stannite more soluble than calcium stannite. and a stabilizing agent for said stannite comprising Rochelle salts.

4. A depilatory compound for use in rapidily removing hair from the human body and containing a soluble stannite as an active depilating agent, an excess of free caustic alkali, and an amphoteric'metal in a form in which reaction will rapidly take place with 10 said free caustic alkali.

5. A depilatory compound for use. in rapidily removing hair from the human body containing a solu 1e stannite as an active depilating agent, an excess of free caustic alkali,

and stannous hydroxid.

6. Adepilatory compound for use in removing hair from the human body which contains as an active depilating agent a soluble stannite of a concentration of approximately 3.5 per cent calculated as SnO.

In a process of compounding a white depilatory containing a stannite more soluble than calicum stannite and for use in removing hair from thehuman body, the steps of preparing the stannite which comprise pre-.

paring stannous hydroxid by reacting stannous chlorid with an alkaline salt and combining the resulting stannous hydroxid with an alkali, and adding a bufi'cr to control the so alkalinity of the compound.

8. In a process of compounding a white depiliatory containing a stannite more soluble than calcium stannite and for use in removing hair from the human body, the steps of preparing the stannite which comprise preparing stannous hydroxid by reacting stannous chlorid with an alkaline salt, washing and then stabilizing the resulting stannous hydroxid, and finally combining the 40 stanno'us hydroxid with an alkali.

In testimony whereof, we have signed our names to this specification this 31st day of December, 1931.

- RALPH H. MoKEE.

. EARLE H. MORSE. 

